Standard rule of thumb for K2SO4 dosing...

[Lukara]

Can anybody shed some light on what it is when dosing in dry form?

For example, I have a 50 gallon and dose 1/2 tsp of K2SO4 weekly after a 50% water change. Is this too little, too much?

thanks!

[Tempest]

Sounds right to me.

[wetmanNY]

Isn't that going to add up to a lot of sulfate after a few weeks?

Dosing depends on how much nutrient the planting has used up. How strongly they are photosynthesizing. How many plants there are...

[djlen]

According to Tom Barr, this is a safe dosing for the size tank, and someone who is doing a 50% water change weekly. Please expand on your thread Wetman.
Len

[Lukara]

Based on Chuck Gadd's calculator, dosing .5 tsp for a 50 gallon tank yields only 7.12 ppm of Potassium in K2SO4 (unless I'm not using it right) so isn't it underdosing?

[wetmanNY]

I don't want to interpret Tom Barr-- or speak for him!-- because he's very knowledgable indeed.

But common sense tells us that dosing rates depends on plant metabolism, strength of the lighting, density of planting, etc. These variables govern how fast nutrients are used, and thus how much and how soon they need to be re-dosed.

Fertilizer doesn't "make plants grow." But strongly growing plants will use up available nutrients, which need to be replaced.

Potassium chloride is more soluble than potassium sulfate. That might be a consideration, since only dissolved nutrients are bioavailable. That's why some nutrients need to be chelated-- in order to remain available...

Depending on your K form, you could have some nitrate, some chloride or some sulfate with your Special K. Which anion do you prefer in your particular situation?

[Lukara]

Well, ok let me ask this question another way then...

Suppose someone is starting a planted tank and has all the necessary requirements for healthy plants all set up (i.e. pressurized CO2, good lighting (2 wpg +), moderate-highly planted tank etc... Suppose the tank set up is oriented towards growing healthy plants (with fishes in it of course!)

You have to start somewhere right? I realize every tank is different you can't have a 1 size fits all solution. What I'm asking is what is the recommended average safe starting point, or at least the minimum dosing amount when adding Potassium from the K2SO4 source? (i.e. 1/4 tsp per 20 gallons?) Comparing the solubility and differences between KCl and K2SO4 is another thread. :D

Thanks.

[djlen]

1/4 tsp. is what I've been using while doing a 50%er every week.
I can only say that I've experienced no problems with it. My plants are growing well, and the fish are fine.
You can draw your own conclusions from that.
Len